<span>A system of equations has infinitely many solutions when the two
lines representing the equations coincide. i.e. the two equations are
the same or a multiple of each other. 2y - 4x = 6 2y = 4x + 6 2y = 2(2x + 3) y = 2x + 3 -y = -(2x + 3) -y = -2x - 3 Hence the other equation is -y = -2x - 3</span>
